When we are young, we seem to have no shortage of “best friends.” As we mature, however, the nature of our friendships changes. Having or being a best friend is no longer as simple as labeling someone our BFF and having them reciprocate.

Other more important factors come into play, including:

Being emotionally supportive. This is probably the most important element of any adult friendship. Best friends refrain from unnecessarily criticizing each other and tend to be nonjudgmental.

A best friend will listen to you and thoughtfully respond rather than react to what you’ve said even if you have triggered something in him or her. The ability to hear what another is truly saying is one of the best parts of friendship.

Best friends go out of their way for the people they care about, and it feels good to both parties. You can tell who your real friends are when you need help with a move or a ride to the airport.

Thoughtfulness is a quality that deepens and strengthens any friendship. Being able to see someone else’s needs—and to do what you can to fulfill those needs—enables bonding experiences. Our best friends do things for us no one else would think of.

Reliability. When you know you can call on your best friend to bail you out of a jam, 24/7, it makes you feel better and increases your overall confidence.

Best friends accept you and all your flaws. They don’t expect perfection. When you aren’t at your best, they are understanding rather than critical. If you’re having a bad day, someone who cares for you will ask if they can help or if they should let you be alone if that’s what you need.

A friend once gave me a cocktail napkin that said, Friends are therapists you can drink with. A good friendship is indeed therapeutic, though a good friend is not the same as a drinking buddy.

A strong friendship defines you both and help each of you navigate this thing called life. Your friend is a mirror who reflects back to you who you are to them. In other words, your best qualities shine, and those pieces that need improvement are not judged but understood.

It’s hard for some of us to cry alone. Instead, we might need a shoulder to cry on, and having a friend you feel comfortable doing that with is a gift. When facing difficulty, having someone you can really let your pain out with can be invaluable.

Best friends have your back. Knowing you can trust another person with your well-being allows you both to explore and enjoy more new things than you would on your own.

It’s life-affirming to have a best friend to help pull you up but never put you down. You have to be willing to give as much as you want to get, but I don’t know anyone who thinks a good friendship is not worth the effort.